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| Home > Publications database > Genetische und physiologische Untersuchungen zur Pantothenat- und Valinbildung in Corynebacterium glutamicum |
| Home > Publications database > Genetische und physiologische Untersuchungen zur Pantothenat- und Valinbildung in Corynebacterium glutamicum |
| Book/Report | FZJ-2019-04549 |
1998
Forschungszentrum Jülich, Zentralbibliothek, Verlag
Jülich
Please use a persistent id in citations: http://hdl.handle.net/2128/22645
Report No.: Juel-3606
Abstract: The Gram-positive bacterium Corynebacterium glutamicum is used for the production of amino acids, e.g. of L-glutamate and L-lysine. The aim of my work was to elucidate the biosynthetic pathway of pantothenic acid of this organism, and to increase the formation of L-valine and D-pantothenic acid in order to enable a microbiological production of these compounds. The genes panB and panC euere cloned, which encode the ketopantoatehydroxy-methyltransferase and the pantothenatesynthetase. The two enzymes catalyze important steps of the biosynthetic pathway of pantothenate. Sequence analysis revealed that panB comprises 813 bp and panC 837 bp. The genes are organized as an operon. Assays for the enzymes of the pathway haue been developed. Thepantothenatesynthetase has a specifc activity of 1 nmol/(min$\ast$mg protein), the ketopantoatehydroxymethyltransferase one of 0.14 nmol/(min$\ast$mg protein) and the aspartate-$\alpha$-decarboxylase one of 0.11 nmol/(min$\ast$mg protein). The quantitative analysis of the formation of pantothenic acid revealed that C. glutamicum accumulates 10 $\mu$g/l pantothenic acid. A system to isolate mutants with an increased formation pantothenate, which is based on a deficiency of pantothenic acid induced by $\alpha$-ketobutyrate, has been established. The application of this method led to the isolation of a mutant which accumulates 250 $\mu$g/l pantothenate and 1.4 g/l valine. Overexpression of the genes of the valine and isoleucine biosynthetic pathway (ilvBNCD), in combination with the deletion of the threonine dehydratase gene ilvA resulted in the construction of a strain which accumulates 11,3 g/l valine and 190 mg/l pantothenate. Additional overexpression of panBC led to an accumulation of up to 1 g/l pantothenic acid. Thus an increase of the formation of pantothenic acid in C. glutamicum by the factor of 10$^{5}$ has been achieved.
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